Written By Doug Smirnoff

Bulls DESERT FALCON EVO S Common Problems and Troubleshooting

For those seeking higher speeds, agility, and precision in their electric bike journeys, the Bulls DESERT FALCON EVO S is the perfect choice. In this article, we’ll address common problems and provide troubleshooting solutions specific to this exceptional model.


Introducing the Desert Falcon EVO, a remarkable electric bike equipped with the new Bosch Gen4 Performance Speed drive unit and Powertube 500Wh battery. This powerhouse allows you to conquer mountain climbs with ease, offering assist speeds of up to 28 mph. The bike’s internal cable routing maintains a sleek appearance, while the top-of-the-line Shimano GRX Di2 Hydraulic Disc groupset ensures rapid and precise electronic shifting, along with refined brake performance.

Product Details and Features

MotorBOSCH Gen4 Performance Speed
BatteryBOSCH PowerTube 500 Wh: 36 V / 13.4 Ah
DisplayBOSCH Kiox
  • Frame: 6061 Aluminum
  • Sizes: 50/55/60cm
  • Fork: BULLS Carbon 1.5″ tapered steer tube
  • Rear Derailleur: Shimano GRX Di2 RD-RX817
  • Gears: 11 speed
  • Shifters: Shimano ST-RX815 Di2
  • Crankset: FSA 48T
  • Cassette: Shimano XT M8000, 11-42T
  • Brakes: Shimano GRX RX810, hydraulic disc brakes, 180mm Fr/Rr
  • Handlebar: FSA Energy SCR Compact
  • Seatpost: BULLS ovalized carbon, 30.9×380
  • Seat: BULLS
  • Wheelset: DT Swiss HE1800 Spline, 20mm int. width, tubeless ready rims
  • Tires: Schwalbe E-One EVO V-Guard 700×32
  • Pedals: Not included
  • Weight: 41.5 lbs.

Causes of Common Problems with the Bulls DESERT FALCON EVO S

1. Motor Not Providing Assistance

Description: You’re experiencing a lack of assistance from the Bosch Gen4 Performance Speed motor.

Cause: Several factors can contribute to this issue, including a disconnected power source, motor errors, or software glitches.


  1. Check the battery connection to ensure it’s properly connected.
  2. Restart the bike and ensure the display shows no motor errors.
  3. If the issue persists, update the motor’s firmware or seek professional assistance.

2. Battery Drains Quickly

Description: The BOSCH PowerTube 500 Wh battery depletes rapidly, reducing your riding range.

Cause: Factors like aggressive riding, extreme terrain, and cold temperatures can contribute to faster battery consumption.


  1. Adjust your riding style to be more energy-efficient, avoiding rapid accelerations.
  2. Avoid extreme weather conditions that can affect battery performance.
  3. If the issue continues, consider investing in a spare battery or upgrading to a higher-capacity one.

3. Shifting Problems

Description: You’re facing issues with the Shimano ST-RX815 Di2 electronic shifting system.

Cause: Misalignment of gears, cable tension, or electronic component malfunction can lead to shifting problems.


  1. Ensure gears are properly aligned by adjusting the derailleur settings.
  2. Check cable tension and make necessary adjustments.
  3. If problems persist, inspect electronic components for damage or connectivity issues.

4. Brake Performance Issues

Description: You notice decreased braking efficiency with the Shimano GRX RX810 hydraulic disc brakes.

Cause: Brake pad wear, air in the brake lines, or rotor issues can impact braking performance.


  1. Inspect brake pads for wear and replace if necessary.
  2. Bleed the brake lines to remove any trapped air bubbles.
  3. Check rotor alignment and ensure it’s not bent or damaged.

5. Display Malfunction

Description: The BOSCH Kiox display is not functioning correctly, affecting your ability to monitor and control the bike.

Cause: Display cable connection issues, software bugs, or physical damage to the display can cause malfunctions.


  1. Check the cable connections between the display and the motor for any loose or damaged cables.
  2. Try resetting the display to its factory settings and updating the software.
  3. If the problem persists, contact Bulls customer support or a certified technician for further diagnosis and repair.

6. Inconsistent Assist Levels

Description: The Bulls DESERT FALCON EVO S provides inconsistent levels of assistance, making your ride unpredictable.

Cause: This issue may arise from sensor malfunctions, wiring problems, or software glitches.


  1. Check the sensor connections and ensure they are securely attached.
  2. Inspect the wiring for any visible damage or loose connections.
  3. If the problem persists, consider resetting the bike’s software or consulting a professional technician.

7. Unusual Noises While Riding

Description: You hear unusual noises coming from your Bulls DESERT FALCON EVO S while riding, affecting the overall experience.

Cause: Noises can result from loose components, chain issues, or even dirt accumulation in crucial parts.


  1. Inspect the bike for loose bolts or components and tighten them as needed.
  2. Lubricate the chain and ensure it’s properly tensioned.
  3. Clean the bike thoroughly to remove dirt and debris that may be causing the noises.

8. Display Error Messages

Description: The BOSCH Kiox display shows error messages that you’re unsure how to resolve.

Cause: Error messages can indicate various issues, such as sensor problems, low battery voltage, or system faults.


  1. Refer to the user manual to interpret the specific error message displayed.
  2. If it’s a sensor issue, check sensor connections and ensure they are functioning correctly.
  3. If the problem remains unresolved, contact Bulls customer support for guidance.

9. Rapid Tire Wear

Description: The Bulls DESERT FALCON EVO S experiences rapid tire wear, necessitating frequent replacements.

Cause: Riding on rough or abrasive terrain, incorrect tire pressure, or misalignment can contribute to tire wear.


  1. Adjust tire pressure according to manufacturer recommendations and regularly check for proper inflation.
  2. Inspect the tires for alignment issues or damage that may be causing premature wear.
  3. If you frequently ride on challenging terrain, consider upgrading to more durable tires.

10. Charging Difficulties

Description: You encounter difficulties while trying to charge the Powertube 500Wh battery.

Cause: Charging problems may stem from faulty charging cables, damaged connectors, or issues with the battery itself.


  1. Inspect the charging cable for any visible damage and replace it if necessary.
  2. Ensure the battery connectors are clean and securely connected.
  3. If the issue persists, contact Bulls customer support or a qualified technician to diagnose and resolve the problem.

11. Excessive Vibration While Riding

Description: You experience noticeable and uncomfortable vibrations while riding your Bulls DESERT FALCON EVO S.

Cause: Excessive vibration can result from misaligned wheels, loose components, or worn-out suspension parts.


  1. Check and adjust the wheel alignment to ensure both wheels are properly seated in the frame.
  2. Inspect and tighten any loose bolts or components, including the handlebars and saddle.
  3. If the issue persists, examine the suspension system for wear and consider servicing or replacement.

12. Poor Battery Life in Cold Weather

Description: The Bulls DESERT FALCON EVO S exhibits reduced battery life during cold weather rides.

Cause: Cold temperatures can temporarily decrease the efficiency of the battery, leading to diminished range.


  1. Store the bike and battery indoors at room temperature before your ride to help maintain its performance.
  2. If riding in cold conditions, carry a spare, fully charged battery to extend your range.
  3. Consider insulating the battery during colder rides to help mitigate temperature-related issues.

13. Unresponsive Display Touchscreen

Description: The touchscreen on the BOSCH Kiox display becomes unresponsive to touch inputs.

Cause: This issue may be due to screen calibration errors, dirt on the screen, or software glitches.


  1. Restart the display and recalibrate the touchscreen in the settings menu.
  2. Clean the screen with a soft, lint-free cloth to remove any dirt or smudges that may hinder responsiveness.
  3. If the problem persists, update the display’s firmware or seek professional assistance.

14. Chain Slippage During Gear Changes

Description: The chain on your Bulls DESERT FALCON EVO S occasionally slips when shifting gears.

Cause: Chain slippage can result from a misaligned derailleur, a worn chain, or improperly adjusted shifters.


  1. Inspect the derailleur and ensure it’s properly aligned with the gears. Make necessary adjustments.
  2. Check the chain for wear and replace it if it has reached its service limit.
  3. Verify that the shifters are correctly adjusted to minimize chain slippage.

15. Excessive Noise from the Motor

Description: The Bosch Gen4 Performance Speed motor produces unusual or loud noises during operation.

Cause: Motor noise can be caused by internal mechanical issues, loose components, or an inadequate lubrication.


  1. Check for loose motor mounting bolts and tighten them securely.
  2. Ensure that the motor is properly lubricated according to the manufacturer’s recommendations.
  3. If the noise persists, contact a certified technician or Bulls customer support for further diagnosis and potential repairs.

16. Uneven Brake Performance

Description: Your Bulls DESERT FALCON EVO S exhibits uneven braking, with one brake feeling stronger or weaker than the other.

Cause: This issue can arise from uneven brake pad wear, hydraulic fluid imbalance, or caliper misalignment.


  1. Inspect the brake pads on both wheels and replace any that are worn unevenly.
  2. Bleed the brake system to ensure hydraulic fluid is evenly distributed between both brakes.
  3. Check the caliper alignment and make necessary adjustments for even braking performance.

17. Display Visibility in Bright Sunlight

Description: The BOSCH Kiox display becomes difficult to read in bright sunlight conditions.

Cause: Sun glare on the display can make it challenging to see important information while riding.


  1. Adjust the display angle to minimize glare by tilting it slightly downward or upward.
  2. Consider using a sunshade or a display cover designed to reduce glare in sunny conditions.
  3. Ensure your sunglasses or riding gear do not contribute to glare and adjust as needed.

18. Loose or Uncomfortable Handlebars

Description: The handlebars on your Bulls DESERT FALCON EVO S feel loose or uncomfortable to grip.

Cause: Improperly tightened handlebar components or handlebar tape issues can lead to discomfort.


  1. Check and tighten all handlebar bolts, including stem and grips, to the manufacturer’s specifications.
  2. If the handlebar tape is uncomfortable, consider re-wrapping it or replacing it with a more comfortable option.
  3. Ensure your handlebar position and grip style are ergonomic for your riding preferences.

19. Difficulty Shifting to Lower Gears

Description: Shifting to lower gears on the Bulls DESERT FALCON EVO S is challenging or unresponsive.

Cause: This issue may result from cable tension problems, misalignment, or worn gear components.


  1. Adjust the cable tension for the rear derailleur to ensure smooth shifting to lower gears.
  2. Inspect the gear alignment and adjust the derailleur if needed to prevent misalignment issues.
  3. If the problem persists, check the condition of the gear components and replace any worn parts.

20. Sudden Loss of Power

Description: While riding, your Bulls DESERT FALCON EVO S experiences a sudden loss of power, leaving you without assistance.

Cause: This issue can be caused by battery disconnection, motor overheating, or a malfunction in the electrical system.


  1. Check the battery connection to ensure it’s securely attached and properly seated.
  2. Allow the motor to cool down if it has overheated, and avoid prolonged periods of high-speed riding.
  3. If the problem persists, consult a qualified technician for a thorough electrical system inspection.

21. Unpredictable Power Cuts

Description: Your Bulls DESERT FALCON EVO S experiences sudden and unpredictable power cuts during rides.

Cause: Power cuts can result from loose electrical connections, battery issues, or sensor malfunctions.


  1. Inspect all electrical connections, including those of the battery, motor, and display, to ensure they are secure.
  2. If power cuts persist, examine the battery for signs of damage or wear and consider replacement if necessary.
  3. Check the sensors for proper functioning and consult a technician if sensor-related issues are suspected.

22. Inaccurate Battery Level Display

Description: The displayed battery level on your Bulls DESERT FALCON EVO S does not accurately reflect the remaining charge.

Cause: This issue can be caused by software bugs, sensor errors, or voltage fluctuations.


  1. Restart the bike and check if the battery level display updates accurately.
  2. If the problem persists, update the bike’s software to the latest version to address potential software-related issues.
  3. If inaccuracies continue, consult a technician to inspect the sensors and electrical system.

23. Difficulty Pairing with Smartphone App

Description: You encounter challenges when attempting to pair your Bulls DESERT FALCON EVO S with the smartphone app for additional features.

Cause: Pairing issues can arise from compatibility problems, Bluetooth connectivity issues, or app-related glitches.


  1. Ensure your smartphone is compatible with the bike’s app and meets the minimum requirements.
  2. Check Bluetooth settings on both the bike and your smartphone, and attempt to pair them again.
  3. If problems persist, contact customer support for the app or Bulls for further assistance.

24. Loose or Noisy Pedals

Description: The pedals on your Bulls DESERT FALCON EVO S feel loose or produce irritating noises during pedaling.

Cause: Loose pedal components, worn bearings, or insufficient lubrication can lead to these issues.


  1. Check the pedal threads and ensure they are properly tightened to the crank arms.
  2. Inspect the pedal bearings for wear or damage and replace if necessary.
  3. Lubricate the pedal components as recommended in the user manual to reduce noise and improve performance.

25. Insufficient Torque or Power

Description: Your Bulls DESERT FALCON EVO S seems to lack the expected torque or power output.

Cause: This issue can result from motor or battery problems, software limitations, or settings adjustments.


  1. Check the motor and battery health, ensuring they are functioning optimally.
  2. Review the bike’s settings and adjust them to the desired power level, if applicable.
  3. If the problem persists, consider consulting with a technician to diagnose and resolve the issue.

Bulls DESERT FALCON EVO S Electric Bike User Reviews

Discover what users have to say about their experiences with the Bulls DESERT FALCON EVO S Electric Bike. We’ve gathered feedback from various sources online, primarily from Walmart, to provide you with a comprehensive overview of customer reviews.

Positive Reviews from Bulls DESERT FALCON EVO S Electric Bike Users

  • Many users were satisfied with the powerful performance of the Bulls DESERT FALCON EVO S, praising its ability to effortlessly tackle steep hills and rough terrain.
  • Several riders expressed appreciation for the bike’s long-lasting battery, allowing them to enjoy extended rides without worrying about running out of power.
  • Users commended the bike’s comfortable and ergonomic design, noting that it provided a smooth and enjoyable riding experience even on longer journeys.
  • Some customers were impressed with the high-quality components and build of the bike, emphasizing its durability and robust construction.
  • Positive remarks were made about the intuitive and user-friendly control interface, making it easy for riders to adjust settings and monitor their progress.

In summary, the majority of users were pleased with their Bulls DESERT FALCON EVO S Electric Bike, highlighting its impressive performance, long battery life, comfort, build quality, and user-friendly features.

Negative User Reviews of the Bulls DESERT FALCON EVO S Electric Bike

  • Some users were not satisfied with the weight of the bike, finding it to be on the heavier side, which made handling and transport more challenging.
  • A few riders reported issues with electronic components, such as the display or electronic shifting, leading to concerns about reliability and the need for potential repairs.
  • Several customers expressed disappointment with the bike’s price point, considering it to be relatively high compared to other electric bikes in the market.
  • Occasional complaints were made about the lack of included pedals, requiring users to purchase them separately.
  • Some riders experienced discomfort with the bike’s saddle, indicating that it may not be suitable for extended rides without additional padding or adjustments.

While the majority of users had positive experiences with the Bulls DESERT FALCON EVO S Electric Bike, there were a few concerns related to its weight, electronic components, pricing, pedal inclusion, and saddle comfort.

Overall, it’s noteworthy that the majority of users expressed satisfaction with the Bulls DESERT FALCON EVO S Electric Bike, highlighting its strong performance and features. However, as with any product, there were some negative experiences and concerns raised by a minority of users.

Bulls DESERT FALCON EVO S Electric Bike Manual

The operating instructions for the Bulls DESERT FALCON EVO S can be found on the manufacturer’s website. You can access the detailed user manual, which provides comprehensive guidance on how to use and maintain your electric bike, ensuring a smooth and trouble-free riding experience.

Bulls DESERT FALCON EVO S Frequently Asked Questions

1. How can I maximize the battery life of my Bulls DESERT FALCON EVO S?

To extend your battery life, avoid exposing it to extreme temperatures, store it in a cool and dry place, and charge it regularly, even if you’re not using the bike. Additionally, ride in lower assistance levels when possible, and maintain proper tire pressure to reduce rolling resistance.

2. What should I do if my electric bike experiences a sudden loss of power?

If you encounter a sudden loss of power, first check the battery’s connection to ensure it’s securely attached. If the issue persists, consult the user manual for troubleshooting steps or contact Bulls customer service or a certified technician for assistance.

3. Can I use the Bulls DESERT FALCON EVO S in heavy rain or wet conditions?

The Bulls DESERT FALCON EVO S is designed to withstand light rain and wet conditions, thanks to its durable construction. However, it’s advisable to avoid riding in heavy downpours to prevent potential water damage to sensitive components. Always dry the bike thoroughly after wet rides.

4. How often should I service my Bulls DESERT FALCON EVO S?

Regular maintenance is essential to keep your electric bike in optimal condition. Follow the maintenance schedule outlined in the user manual. Generally, it’s recommended to have your bike serviced annually or after approximately 1,000 miles of riding, but this can vary depending on usage and conditions.

5. What should I do if I encounter an issue not covered in the user manual?

If you face a problem that is not addressed in the user manual, it’s advisable to reach out to Bulls customer service or a certified service center for expert assistance. They can help diagnose and resolve more complex issues and provide guidance on troubleshooting.


For any problems or concerns with your Bulls DESERT FALCON EVO S, always refer to the user manual for guidance on troubleshooting and maintenance. Additionally, don’t hesitate to reach out to customer service or visit a certified service center when encountering issues beyond your expertise. Keeping your electric bike in top condition ensures a safer and more enjoyable riding experience.

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